EIPH: If You’re not Breezing, You’re Bleeding

Allen Jerkens pointed to a fitter, sturdier animal as another reason why bleeding was considered atypical in the 1950’s and 1960’s. He said none of his good horses were bleeders.

“Horses worked a lot harder in those days,” he said. “The strain on them in the race wasn’t as much as the strain is on them now. They trained almost as hard in the morning as they did when they ran.”

The best horses would often work the full distance of an upcoming race five or six days before, breeze a half-mile two days out, and maybe even an eighth of a mile the morning of the race. As but one example, three days before Assault finished off the Triple Crown, Max Hirsch sent the colt out for a 12-furlong breeze in 2:32 at Belmont.

-above from yesterday’s DRF article: http://www.drf.com/news/lasix-demystifying-drug-methods-training-without-it

Why do some horses bleed enough to negatively impact performance, while others do not?

We’ve been down this road many times on this blog, but the recent attention paid to the future of Lasix in US racing begs us to take a more detailed look at the role of conditioning and its effects on bleeding/EIPH. One point of this post is that every drug in the history of the world has negative side effects, some that take years to be discovered. Lasix is no exception. Drugs are shortcuts, meant to make things easier on the trainer and owner, often at the expense of the horse itself.

Look at this image above of a horse’s lungs; on your left is the cut-away view where you can begin to see the branching off of networks of blood vessels. After dozens of successive divisions, these vessels become smaller and smaller, eventually ending in air sacs called alveoli. Covering each air sac is a tiny network of blood vessels called capillaries. How thin is the skin of an air sac? About 1% of the thickness of a human hair – that is all that separates the air sacs of the lungs from the blood found in the capillaries. No wonder this membrane breaks under pressure!

If we take all the alveoli in a horse and spread them out we end up with a surface area equal to that of about 10 tennis courts – all this space is where the actual movement of oxygen from the lungs finds its way into the bloodstream. The number of capillaries surrounding these ’10 tennis courts of air sacs’ is believe to be around….300 billion, wow.

Back to conditioning, exercise, and its role in EIPH. Even at a walk, trot, or slow canter some capillaries are bursting. When the lungs are being buffeted by the other internal organs during a gallop even more pulmonary capillaries are exploding with each step. This is inevitable and is the basis for the statement; ‘all horses bleed’. Lasix lessens, but does not prevent, this occurrence. And this ‘lessening’ is vitally important, but also achievable by a logically progressing dose of exercise at speed – as we will soon see.

Think of these alveoli, or air sacs, as balloons coated in a network of blood-filled capillaries. Remember, these balloons are going to burst even at a jog or slow gallop, probably even moreso over a hard dirt surface as compared to synthetics or turf. The key question becomes: How do I manage training to avoid ‘popping’ a significant number of these balloons at any one time – resulting in a bleeding episode significant enough to hamper performance?

Well, the solution is most certainly not to breeze a 2yo up to 4F from a rolling start and then throw him in the gate for a maiden effort at 6F+. At the start of this 2yo’s conditioning regimen, everything is actually perfect. Many of the FL breakers of these juveniles follow a sensible, scientific method of progressive overload meant to avoid bucked shins and grow strong bone as detailed here:


Again, perfect! In order to avoid shin soreness due to a sudden increase in the training load; breezes start at perhaps 1F/:17 and systematically progresses to 4F/:50. An unintended side effect is that you also get optimal development of soft tissues such as ligaments and tendons. Notice that the proven frequency needed to progressively grow dense ‘racing’ bone is a bout of speed every 5 days or less, any longer and you lose the cumulative effects of the exercise. Unfortunately, burst capillaries due to EIPH do NOT regenerate themselves as does bone, that would make our job so much easier.

Many top thoroughbreds are getting Lasix at this point as a preventative measure, but it’s not necessary for most due to the gradual increase of the exercise load at speed. Keep in mind this is a key time for skeletal development, and 25+ Lasix shots accompanied by the associated leaching of calcium (a crucial bone builder) is probably not wise. Here is where the shortcut to avoid problems in one physiological system exerts negative effects on another as US turf runners breakdown 3x more often than those in Australia:


If you choose not to believe the use of Lasix contributes to US horses being the most fragile worldwide, that is your right – but you are also then of the belief that Lasix/Salix is the only drug in the history of the world to produce no negative side effects. C’mon you are most likely a bettor, what are the odds of this? 2,000-1?

Sure, possibly millions of alveoli/air sacs/balloons are bursting during each breeze session, but never a billion at one time are exploding and causing a Grade 4 episode:

Grades of EIPH (Photos courtesy of Dr. Ken Hinchcliff, DVM):

Grade 0 – no bleeding visible during scope – fantastic





Grade 1 – flecks of blood, or single stream found in trachea – stinks, but even humans can bleed this much, performance unaffected





Grade 2 – multiple streams of blood, but covering less than 1/3 of tracheal surface – the dividing line – some horses impacted, others not so much





Grade 3 – multiple streams of blood covering over 1/3 of tracheal surface – probably no fun for a racing horse at all as performance is being negatively impacted





Grade 4 – blood everywhere, a virtual slaughterhouse – performance definitely compromised, nasal bleeding evident in many instances

Even under the liberal use of Lasix, Grade 1-2 bleeds will be common. What we hope to avoid is the Grade 3-4 episodes, and nearly every horse conditioned to breeze 4F in :50 from a rolling start now expected to race 6F in 1:10 from a gaited start is going to bleed significantly, likely suffering from the first significant lung bleeds in his/her young life.

Move ahead to the 3yo campaign: classic contenders are now racing 8-9F, but still mostly breezing 4-5F in training. That was emphatically not the case in the days of Allen Jerkens, Max Hirsch, Assault, and pretty much every other Triple Crown winner in American history.

So, if a trainer is scoping a horse after every breeze and race, that is a good thing, but one must act on that intelligence in a practical manner.

When you are breezing 4F without Lasix and getting Grade 0 or 1 bleeding episodes – move to 5F when all other systems say ‘go’. You will possibly see a Grade 2 episode, followed by Grade 1’s and 0’s…..now work 6F and begin the process again.

On the flip side, if you continue to breeze only 4-5 panels and race 6-8+, expect multiple Grade 3’s, and get that syringe ready.

Hell, in the time it would have taken a vet to research and write this post this morning, he could have given 20 Lasix shots at $12ea on the backside for a trainer’s breeze day. I can’t blame him, medical intervention to solve problems is the basis of their education/training and now their manner of making a living – but you wouldn’t ask your cardiologist to train your son for a 400m race, would you?

In summary, all horses bleed, and if we are going to race them, they are going to bleed more. Yes, controlling these episodes is necessary and humane, but Lasix is a shortcut that most likely diminishes proper skeletal development at its most crucial stages – and the same effects can be achieved through the conditioning protocol of the old timers.

P.S. Want to see this concept in action (minus the repeated scoping)? Check out a 22yo vet student and his training diary:



About bpressey

Equine Exercise Physiologist

Posted on November 18, 2011, in Uncategorized. Bookmark the permalink. 3 Comments.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )


Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.

%d bloggers like this: